Polyphenols are an incredibly diverse group of compounds (Ferriera et al., ‘Diversity of Structure and Function in Oligomeric Flavanoids, Tetrahedron, 48:10, 1743–1803, 1992). They widely occur in a variety of plants, some of which enter into the food chain. In some cases they represent an important class of compounds for the human diet. Although some of the polyphenols are considered to be non-nutritive, interest in these compounds has arisen because of their possible beneficial effects on health.
For instance, quercetin (a flavonoid) has been shown to possess anticarcinogenic activity in experimental animal studies (Deshner et al., ‘Quercertin and Rutin as Inhibitors of Azoxymethanol-induced Colonic Neoplasia’, Carcinogenesis, 7:1193–1196, 1991: and Kato et al., ‘Inhibition of 12-O-tetradecanoylphorbol-13-acetate Induced Tumor Promotion and Ornithine Decarboxylase Activity by Quercitin: Possible Involvement of lipoxygenase Inhibition’, Carcinogenesis, 4, 1301–1305 1983). (+)-catechin and (−)-epicatechin (flavan-3-ols) have been shown in inhibit Leukemia virus reverse transcriptase activity (Chu et al., Inhibitory Effects of Flavonoids on Maloney Murine Leukemia Virus Reverse Transcriptase Activity, J. of Natural Products, 55:2, 179–183, 1992). Nobotanin (an oligomeric hydrolyzable tannin) has also been shown to possess anti-tumor activity (Okuda et al., ‘Molecular Structures and Pharmacological Activities of Polyphenols—Oligomeric Hydrolyzable Tannins and Others'—Presented at the XVIth International Conference of the Groupe Polyphenols, Lisbon, Portugal, Jul. 13–16, 1992). Statistical reports have also shown that stomach cancer mortality is significantly lower in the tea producing districts of Japan. Epigallocatechin gallate has been reported to be the pharmacologically active material in green tea that inhibits mouse skin tumors (Okuda et al, ‘Molecular Structures and Pharmacological Activities of Polyphenols—Oligomeric Hydrolyzable Tannins and others. Presented at the XVIth International Conference of the Groupe polyphenols, Lisbon, Portugal, 1992). Osakabe et al. (JP 7274894 “Food and Drink For Preventing Gastric Ulcers—Contains Antioxidation Substance Extracted from Cacao Beans using Hot Water or Ethanol” October 1995; JP 7213251 “Method on Manufacturing an Antioxidation Substance and a Health Food or Drink Item Containing an Antioxidation Substance” August 1995) have reported that the antioxidant properties of cocoa bean extract, thought to contain epicatechin and analogous compounds, are responsible for inhibiting formation of gastric ulcers in rats. Ellagic acid has also been shown to possess anticarcinogen activity in various animal tumor models (Boukharta et al., Efficacy of Ellagitannins and Ellagic Acid as Cancer Chemopreventive Agents—Presented at the XVIth International Conference of the Groupe Polyphenols, Lisbon, Portugal, Jul. 13–16, 1992). Lastly, proanthocyanidin oligomers have been reported by the Kikkoman Corporation for use as antimutagens (‘Antimutagenic Agent Containing Proanthocyanidin Oligomer Preferably Having Flavan-3-ol-diol Structure’ JP 04190774A, Jul. 7, 1992). Indeed, the area of phenolic compounds in foods and their modulation of tumor development in experimental animal models has been recently presented to the 202nd National Meeting of The American Chemical Society (Phenolic Compounds in Foods and Their Effects on Health II. Antioxidants & Cancer Prevention, Huang, M.-T., Ho, C.-T., and Lee, C. Y. editors, ACS Symposium Series 507, Am. Chem. Soc., Washington, D.C. 1992).